Problem: $-\dfrac{1}{6} - \dfrac{7}{4} = {?}$
Solution: $ = - {\dfrac{1 \times 2}{6 \times 2}} - {\dfrac{7 \times 3}{4 \times 3}} $ $ = - {\dfrac{2}{12}} - {\dfrac{21}{12}} $ $ = - \dfrac{{2} - {21}}{12} $ $ = -\dfrac{23}{12}$